Reportable Segments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Oct. 02, 2011	Jul. 03, 2011	Apr. 03, 2011	Jan. 02, 2011	Oct. 03, 2010	Jun. 27, 2010	Mar. 28, 2010	Dec. 27, 2009	Oct. 02, 2011	Oct. 03, 2010	Sep. 27, 2009
Revenue by client sector
Revenue	$ 675,662	$ 673,792	$ 612,566	$ 611,124	$ 627,382	$ 562,365	$ 469,528	$ 541,957	$ 2,573,144	$ 2,201,232	$ 2,287,484
Federal government
Revenue by client sector
Threshold percentage for disclosure of revenue from a single client									10.00%
Revenue									1,115,729	1,142,082	1,164,751
State and local government
Revenue by client sector
Revenue									282,941	325,953	277,756
Commercial
Revenue by client sector
Revenue									577,782	523,723	740,491
International
Revenue by client sector
Revenue									$ 596,692	$ 209,474	$ 104,486